In recent times, in order to prevent vehicle theft, many vehicles are equipped with security alarm systems. In such alarm systems, the vehicle typically has an intrusion detector such as the vehicle impact sensor for detecting a vibration of the vehicle caused by an intrusion event on the vehicle. When the detector detects the intrusion, it activates an alert device. A warning is then accomplished through the alert device with the loud alarm alerts and the flashing of lights (hazard light flashing).
For such security alarm systems, local ordinances typically prescribe the times for which such alarm alerts can continue, in order to reduce noise pollution and to prevent depletion of the car battery and other attendant problems.
U.S. Pat. No. 5,157,375 discloses a security alarm system in which the alarm alert is stopped after continuing for a certain time period, and it is prevented from resuming until the system is either armed again or disarmed. That is, if the alert continues for a set period of time, unless the system is disarmed and armed again, the security alarm system will no longer operate.
However, with the invention disclosed in U.S. Pat. No. 5,157,375, after alerts based on the same sensor have sounded for a certain period of time, any audible alerts based on that specific sensor may be stopped. Thus, a problem results in that the effectiveness of such alerts in preventing theft is reduced.
Therefore, a security alarm system for vehicles which can continue providing alerts to maximize deterrence of unauthorized intruders, while still reducing the potential for undesirable repetitions of alarm cycles, is highly desired.